<!DOCTYPE html>
<html lang="zh-CN" dir="ltr">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,initial-scale=1">
    <title>对象 | 静思田园</title>
    <meta name="description" content="时不时记录一点点">
    <meta name="generator" content="VitePress v1.5.0">
    <link rel="preload stylesheet" href="/assets/style.D1KHeDuB.css" as="style">
    <link rel="preload stylesheet" href="/vp-icons.css" as="style">
    <script type="module" src="/assets/chunks/metadata.d4b76d32.js"></script>
    <script type="module" src="/assets/app.Cqoht_Of.js"></script>
    <link rel="preload" href="/assets/inter-roman-latin.Di8DUHzh.woff2" as="font" type="font/woff2" crossorigin="">
    <link rel="modulepreload" href="/assets/chunks/framework.trnLO_3_.js">
    <link rel="modulepreload" href="/assets/chunks/theme.BNMYWj-o.js">
    <link rel="modulepreload" href="/assets/chunks/katex.BZy9Y_85.js">
    <link rel="modulepreload" href="/assets/chunks/c4Diagram-3d4e48cf.rhyfUO3k.js">
    <link rel="modulepreload" href="/assets/chunks/flowDiagram-66a62f08.BvVfKYLl.js">
    <link rel="modulepreload" href="/assets/chunks/flowDiagram-v2-96b9c2cf.rYAPEXyw.js">
    <link rel="modulepreload" href="/assets/chunks/erDiagram-9861fffd.CQSbaoJM.js">
    <link rel="modulepreload" href="/assets/chunks/gitGraphDiagram-72cf32ee.CjLmC8RV.js">
    <link rel="modulepreload" href="/assets/chunks/ganttDiagram-c361ad54.R_V-FeK5.js">
    <link rel="modulepreload" href="/assets/chunks/infoDiagram-f8f76790.C-2Va9KZ.js">
    <link rel="modulepreload" href="/assets/chunks/pieDiagram-8a3498a8.B9ZVkD7K.js">
    <link rel="modulepreload" href="/assets/chunks/quadrantDiagram-120e2f19.BuonnDHi.js">
    <link rel="modulepreload" href="/assets/chunks/xychartDiagram-e933f94c.C_bIYaUn.js">
    <link rel="modulepreload" href="/assets/chunks/requirementDiagram-deff3bca.RFVzvdjl.js">
    <link rel="modulepreload" href="/assets/chunks/sequenceDiagram-704730f1.UZWxMlyq.js">
    <link rel="modulepreload" href="/assets/chunks/classDiagram-70f12bd4.sipmPMFa.js">
    <link rel="modulepreload" href="/assets/chunks/classDiagram-v2-f2320105.CDkLxQ0T.js">
    <link rel="modulepreload" href="/assets/chunks/stateDiagram-587899a1.CD2ocVZB.js">
    <link rel="modulepreload" href="/assets/chunks/stateDiagram-v2-d93cdb3a.D0qUPm3J.js">
    <link rel="modulepreload" href="/assets/chunks/journeyDiagram-49397b02.CeUUZA2l.js">
    <link rel="modulepreload" href="/assets/chunks/flowchart-elk-definition-4a651766.DkdgpMTf.js">
    <link rel="modulepreload" href="/assets/chunks/timeline-definition-85554ec2.WL9yxus9.js">
    <link rel="modulepreload" href="/assets/chunks/mindmap-definition-fc14e90a.CWC2bxmB.js">
    <link rel="modulepreload" href="/assets/chunks/sankeyDiagram-04a897e0.BXj8OViR.js">
    <link rel="modulepreload" href="/assets/chunks/blockDiagram-38ab4fdb.CPVnJXk5.js">
    <link rel="modulepreload" href="/assets/chunks/virtual_mermaid-config.DDnGl6nM.js">
    <link rel="modulepreload" href="/assets/frontend_js基础_对象.md.D3WUEYCU.lean.js">
    <meta name="application-name" content="VuePress">
    <meta name="apple-mobile-web-app-title" content="静思田园">
    <meta name="apple-mobile-web-app-status-bar-style" content="black">
    <meta name="msapplication-TileColor" content="#3eaf7c">
    <meta name="theme-color" content="#646cff">
    <meta name="HandheldFriendly" content="True">
    <meta name="MobileOptimized" content="320">
    <script id="check-dark-mode">(()=>{const e=localStorage.getItem("vitepress-theme-appearance")||"auto",a=window.matchMedia("(prefers-color-scheme: dark)").matches;(!e||e==="auto"?a:e==="dark")&&document.documentElement.classList.add("dark")})();</script>
    <script id="check-mac-os">document.documentElement.classList.toggle("mac",/Mac|iPhone|iPod|iPad/i.test(navigator.platform));</script>
  </head>
  <body>
    <div id="app"><div class="Layout" data-v-5d98c3a5><!--[--><!--]--><!--[--><span tabindex="-1" data-v-0f60ec36></span><a href="#VPContent" class="VPSkipLink visually-hidden" data-v-0f60ec36> Skip to content </a><!--]--><!----><header class="VPNav" data-v-5d98c3a5 data-v-ae24b3ad><div class="VPNavBar" data-v-ae24b3ad data-v-6aa21345><div class="wrapper" data-v-6aa21345><div class="container" data-v-6aa21345><div class="title" data-v-6aa21345><div class="VPNavBarTitle has-sidebar" data-v-6aa21345 data-v-1168a8e4><a class="title" href="/" data-v-1168a8e4><!--[--><!--]--><!--[--><img class="VPImage logo" src="/logo.png" alt data-v-8426fc1a><!--]--><span data-v-1168a8e4>静思田园</span><!--[--><!--]--></a></div></div><div class="content" data-v-6aa21345><div class="content-body" data-v-6aa21345><!--[--><!--]--><div class="VPNavBarSearch search" data-v-6aa21345><!--[--><!----><div id="local-search"><button type="button" class="DocSearch DocSearch-Button" aria-label="搜索文档"><span class="DocSearch-Button-Container"><span class="vp-icon DocSearch-Search-Icon"></span><span class="DocSearch-Button-Placeholder">搜索文档</span></span><span class="DocSearch-Button-Keys"><kbd class="DocSearch-Button-Key"></kbd><kbd class="DocSearch-Button-Key">K</kbd></span></button></div><!--]--></div><nav aria-labelledby="main-nav-aria-label" class="VPNavBarMenu menu" data-v-6aa21345 data-v-dc692963><span id="main-nav-aria-label" class="visually-hidden" data-v-dc692963> Main Navigation </span><!--[--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57></span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/network/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>网络工程师</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/frontend/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>前端</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/English/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>English</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/Scrupy/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>爬虫</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/backend/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>后端</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/bigdata/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>大数据</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/computer/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>计算机基础</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/database/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>数据库</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/docker/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>dorker</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/git/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>Git</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/nodejs/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>Node.js</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/python/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>Python</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/shell/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>shell</span><!--]--></a><!--]--><!--[--><a class="VPLink link VPNavBarMenuLink" href="/tools/" tabindex="0" data-v-dc692963 data-v-e56f3d57><!--[--><span data-v-e56f3d57>工具</span><!--]--></a><!--]--><!--]--></nav><!----><div class="VPNavBarAppearance appearance" data-v-6aa21345 data-v-6c893767><button class="VPSwitch VPSwitchAppearance" type="button" role="switch" title aria-checked="false" data-v-6c893767 data-v-5337faa4 data-v-1d5665e3><span class="check" data-v-1d5665e3><span class="icon" data-v-1d5665e3><!--[--><span class="vpi-sun sun" data-v-5337faa4></span><span class="vpi-moon moon" data-v-5337faa4></span><!--]--></span></span></button></div><div class="VPSocialLinks VPNavBarSocialLinks social-links" data-v-6aa21345 data-v-0394ad82 data-v-7bc22406><!--[--><a class="VPSocialLink no-icon" href="https://github.com/loveagri" aria-label="github" target="_blank" rel="noopener" data-v-7bc22406 data-v-bd121fe5><span class="vpi-social-github"></span></a><a class="VPSocialLink no-icon" href="https://gitee.com/loveagri" aria-label target="_blank" rel="noopener" data-v-7bc22406 data-v-bd121fe5><svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><title>码云</title><path d="M11.984 0A12 12 0 0 0 0 12a12 12 0 0 0 12 12 12 12 0 0 0 12-12A12 12 0 0 0 12 0a12 12 0 0 0-.016 0zm6.09 5.333c.328 0 .593.266.592.593v1.482a.594.594 0 0 1-.593.592H9.777c-.982 0-1.778.796-1.778 1.778v5.63c0 .327.266.592.593.592h5.63c.982 0 1.778-.796 1.778-1.778v-.296a.593.593 0 0 0-.592-.593h-4.15a.592.592 0 0 1-.592-.592v-1.482a.593.593 0 0 1 .593-.592h6.815c.327 0 .593.265.593.592v3.408a4 4 0 0 1-4 4H5.926a.593.593 0 0 1-.593-.593V9.778a4.444 4.444 0 0 1 4.445-4.444h8.296Z"/></svg></a><!--]--></div><div class="VPFlyout VPNavBarExtra extra" data-v-6aa21345 data-v-bb2aa2f0 data-v-cf11d7a2><button type="button" class="button" aria-haspopup="true" aria-expanded="false" aria-label="extra navigation" data-v-cf11d7a2><span class="vpi-more-horizontal icon" data-v-cf11d7a2></span></button><div class="menu" data-v-cf11d7a2><div class="VPMenu" data-v-cf11d7a2 data-v-b98bc113><!----><!--[--><!--[--><!----><div class="group" data-v-bb2aa2f0><div class="item appearance" data-v-bb2aa2f0><p class="label" data-v-bb2aa2f0>Appearance</p><div class="appearance-action" data-v-bb2aa2f0><button class="VPSwitch VPSwitchAppearance" type="button" role="switch" title aria-checked="false" data-v-bb2aa2f0 data-v-5337faa4 data-v-1d5665e3><span class="check" data-v-1d5665e3><span class="icon" data-v-1d5665e3><!--[--><span class="vpi-sun sun" data-v-5337faa4></span><span class="vpi-moon moon" data-v-5337faa4></span><!--]--></span></span></button></div></div></div><div class="group" data-v-bb2aa2f0><div class="item social-links" data-v-bb2aa2f0><div class="VPSocialLinks social-links-list" data-v-bb2aa2f0 data-v-7bc22406><!--[--><a class="VPSocialLink no-icon" href="https://github.com/loveagri" aria-label="github" target="_blank" rel="noopener" data-v-7bc22406 data-v-bd121fe5><span class="vpi-social-github"></span></a><a class="VPSocialLink no-icon" href="https://gitee.com/loveagri" aria-label target="_blank" rel="noopener" data-v-7bc22406 data-v-bd121fe5><svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><title>码云</title><path d="M11.984 0A12 12 0 0 0 0 12a12 12 0 0 0 12 12 12 12 0 0 0 12-12A12 12 0 0 0 12 0a12 12 0 0 0-.016 0zm6.09 5.333c.328 0 .593.266.592.593v1.482a.594.594 0 0 1-.593.592H9.777c-.982 0-1.778.796-1.778 1.778v5.63c0 .327.266.592.593.592h5.63c.982 0 1.778-.796 1.778-1.778v-.296a.593.593 0 0 0-.592-.593h-4.15a.592.592 0 0 1-.592-.592v-1.482a.593.593 0 0 1 .593-.592h6.815c.327 0 .593.265.593.592v3.408a4 4 0 0 1-4 4H5.926a.593.593 0 0 1-.593-.593V9.778a4.444 4.444 0 0 1 4.445-4.444h8.296Z"/></svg></a><!--]--></div></div></div><!--]--><!--]--></div></div></div><!--[--><!--]--><button type="button" class="VPNavBarHamburger hamburger" aria-label="mobile navigation" aria-expanded="false" aria-controls="VPNavScreen" data-v-6aa21345 data-v-e5dd9c1c><span class="container" data-v-e5dd9c1c><span class="top" data-v-e5dd9c1c></span><span class="middle" data-v-e5dd9c1c></span><span class="bottom" data-v-e5dd9c1c></span></span></button></div></div></div></div><div class="divider" data-v-6aa21345><div class="divider-line" data-v-6aa21345></div></div></div><!----></header><div class="VPLocalNav has-sidebar empty" data-v-5d98c3a5 data-v-a6f0e41e><div class="container" data-v-a6f0e41e><button class="menu" aria-expanded="false" aria-controls="VPSidebarNav" data-v-a6f0e41e><span class="vpi-align-left menu-icon" data-v-a6f0e41e></span><span class="menu-text" data-v-a6f0e41e>Menu</span></button><div class="VPLocalNavOutlineDropdown" style="--vp-vh:0px;" data-v-a6f0e41e data-v-17a5e62e><button data-v-17a5e62e>Return to top</button><!----></div></div></div><aside class="VPSidebar" data-v-5d98c3a5 data-v-319d5ca6><div class="curtain" data-v-319d5ca6></div><nav class="nav" id="VPSidebarNav" aria-labelledby="sidebar-aria-label" tabindex="-1" data-v-319d5ca6><span class="visually-hidden" id="sidebar-aria-label" data-v-319d5ca6> Sidebar Navigation </span><!--[--><!--]--><!--[--><div class="no-transition group" data-v-c40bc020><section class="VPSidebarItem level-0 has-active" data-v-c40bc020 data-v-b7550ba0><div class="item" role="button" tabindex="0" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><h2 class="text" data-v-b7550ba0>js基础知识</h2><!----></div><div class="items" data-v-b7550ba0><!--[--><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js基础/" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>js基础知识</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/DOM.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>DOM</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/Map.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>Map</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/Promise.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>Promise</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/Set.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>Set</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/Symbol.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>Symbol</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E4%BA%8B%E4%BB%B6.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>事件</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E4%BB%BB%E5%8A%A1%E7%AE%A1%E7%90%86.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>任务管理</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%87%BD%E6%95%B0%E8%BF%9B%E9%98%B6.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>函数进阶</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%8E%9F%E5%9E%8B%E4%B8%8E%E7%BB%A7%E6%89%BF.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>原型与继承</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%9F%BA%E6%9C%AC%E7%B1%BB%E5%9E%8B.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>基本类型</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%AF%B9%E8%B1%A1.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>对象</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%B8%B8%E7%94%A8%E6%8A%80%E5%B7%A7.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>常用技巧</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E6%95%B0%E7%BB%84%E7%B1%BB%E5%9E%8B.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>数组类型</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E6%A8%A1%E5%9D%97%E8%AE%BE%E8%AE%A1.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>模块设计</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E6%AD%A3%E5%88%99%E8%A1%A8%E8%BE%BE%E5%BC%8F.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>正则表达式</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E7%A9%BA%E9%97%B4%E5%9D%90%E6%A0%87.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>空间坐标</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E7%B1%BB.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>类</p><!--]--></a><!----></div><!----></div><div class="VPSidebarItem level-1 is-link" data-v-b7550ba0 data-v-b7550ba0><div class="item" data-v-b7550ba0><div class="indicator" data-v-b7550ba0></div><a class="VPLink link link" href="/frontend/js%E5%9F%BA%E7%A1%80/%E8%BF%AD%E4%BB%A3%E5%99%A8.html" data-v-b7550ba0><!--[--><p class="text" data-v-b7550ba0>迭代器</p><!--]--></a><!----></div><!----></div><!--]--></div></section></div><!--]--><!--[--><!--]--></nav></aside><div class="VPContent has-sidebar" id="VPContent" data-v-5d98c3a5 data-v-1428d186><div class="VPDoc has-sidebar has-aside" data-v-1428d186 data-v-39a288b8><!--[--><!--]--><div class="container" data-v-39a288b8><div class="aside" data-v-39a288b8><div class="aside-curtain" data-v-39a288b8></div><div class="aside-container" data-v-39a288b8><div class="aside-content" data-v-39a288b8><div class="VPDocAside" data-v-39a288b8 data-v-3f215769><!--[--><!--]--><!--[--><!--]--><nav aria-labelledby="doc-outline-aria-label" class="VPDocAsideOutline" data-v-3f215769 data-v-a5bbad30><div class="content" data-v-a5bbad30><div class="outline-marker" data-v-a5bbad30></div><div aria-level="2" class="outline-title" id="doc-outline-aria-label" role="heading" data-v-a5bbad30>目录</div><ul class="VPDocOutlineItem root" data-v-a5bbad30 data-v-b933a997><!--[--><!--]--></ul></div></nav><!--[--><!--]--><div class="spacer" data-v-3f215769></div><!--[--><!--]--><!----><!--[--><!--]--><!--[--><!--]--></div></div></div></div><div class="content" data-v-39a288b8><div class="content-container" data-v-39a288b8><!--[--><!--]--><main class="main" data-v-39a288b8><div style="position:relative;" class="vp-doc _frontend_js%E5%9F%BA%E7%A1%80_%E5%AF%B9%E8%B1%A1" data-v-39a288b8><div><h1 id="对象" tabindex="-1">对象 <a class="header-anchor" href="#对象" aria-label="Permalink to &quot;对象&quot;">​</a></h1><h2 id="对象转换" tabindex="-1">对象转换 <a class="header-anchor" href="#对象转换" aria-label="Permalink to &quot;对象转换&quot;">​</a></h2><h3 id="symbol-toprimitive" tabindex="-1">Symbol.toPrimitive <a class="header-anchor" href="#symbol-toprimitive" aria-label="Permalink to &quot;Symbol.toPrimitive&quot;">​</a></h3><p>内部自定义<code>Symbol.toPrimitive</code>方法用来处理所有的转换场景</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> hd</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">  num</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">1</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#ABB2BF;">  [</span><span style="color:#E5C07B;">Symbol</span><span style="color:#E06C75;">.toPrimitive</span><span style="color:#ABB2BF;">]: </span><span style="color:#C678DD;">function</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#C678DD;">    return</span><span style="color:#E5C07B;"> this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">num</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#ABB2BF;">  }</span></span>
<span class="line"><span style="color:#ABB2BF;">};</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">hd</span><span style="color:#56B6C2;"> +</span><span style="color:#D19A66;"> 3</span><span style="color:#ABB2BF;">); </span><span style="color:#7F848E;font-style:italic;">//4</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><h3 id="valueof-tostring" tabindex="-1">valueOf/toString <a class="header-anchor" href="#valueof-tostring" aria-label="Permalink to &quot;valueOf/toString&quot;">​</a></h3><p>可以自定义<code>valueOf</code> 与 <code>toString</code> 方法用来转换，转换并不限制返回类型。</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> hd</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">  name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;love&quot;</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">  num</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">1</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#61AFEF;">  valueOf</span><span style="color:#ABB2BF;">: </span><span style="color:#C678DD;">function</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#E5C07B;">    console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;valueOf&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#C678DD;">    return</span><span style="color:#E5C07B;"> this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">num</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#ABB2BF;">  },</span></span>
<span class="line"><span style="color:#61AFEF;">  toString</span><span style="color:#ABB2BF;">: </span><span style="color:#C678DD;">function</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#E5C07B;">    console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;toString&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#C678DD;">    return</span><span style="color:#E5C07B;"> this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#ABB2BF;">  }</span></span>
<span class="line"><span style="color:#ABB2BF;">};</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">hd</span><span style="color:#56B6C2;"> +</span><span style="color:#D19A66;"> 3</span><span style="color:#ABB2BF;">); </span><span style="color:#7F848E;font-style:italic;">//valueOf 4</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">`</span><span style="color:#C678DD;">${</span><span style="color:#E06C75;">hd</span><span style="color:#C678DD;">}</span><span style="color:#98C379;"> you`</span><span style="color:#ABB2BF;">); </span><span style="color:#7F848E;font-style:italic;">//toString love you</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h3 id="默认值" tabindex="-1">默认值 <a class="header-anchor" href="#默认值" aria-label="Permalink to &quot;默认值&quot;">​</a></h3><p>为变量设置默认值</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#ABB2BF;"> [</span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;">site</span><span style="color:#56B6C2;"> =</span><span style="color:#98C379;"> &#39;love&#39;</span><span style="color:#ABB2BF;">] </span><span style="color:#56B6C2;">=</span><span style="color:#ABB2BF;"> [</span><span style="color:#98C379;">&#39;you&#39;</span><span style="color:#ABB2BF;">]</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">site</span><span style="color:#ABB2BF;">) </span><span style="color:#7F848E;font-style:italic;">//love</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><h2 id="属性管理" tabindex="-1">属性管理 <a class="header-anchor" href="#属性管理" aria-label="Permalink to &quot;属性管理&quot;">​</a></h2><h3 id="检测属性" tabindex="-1">检测属性 <a class="header-anchor" href="#检测属性" aria-label="Permalink to &quot;检测属性&quot;">​</a></h3><p><code>hasOwnProperty</code>检测对象自身是否包含指定的属性，不检测原型链上继承的属性。</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> obj</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> { </span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&#39;love&#39;</span><span style="color:#ABB2BF;">};</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">obj</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">hasOwnProperty</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&#39;name&#39;</span><span style="color:#ABB2BF;">)); </span><span style="color:#7F848E;font-style:italic;">//true</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><p>使用 <code>in</code> 可以在原型对象上检测</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> arr</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> [</span><span style="color:#98C379;">&quot;love&quot;</span><span style="color:#ABB2BF;">];</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">arr</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">arr</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">hasOwnProperty</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;length&quot;</span><span style="color:#ABB2BF;">)); </span><span style="color:#7F848E;font-style:italic;">//true</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">arr</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">hasOwnProperty</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;concat&quot;</span><span style="color:#ABB2BF;">)); </span><span style="color:#7F848E;font-style:italic;">//false</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;concat&quot;</span><span style="color:#C678DD;"> in</span><span style="color:#E06C75;"> arr</span><span style="color:#ABB2BF;">); </span><span style="color:#7F848E;font-style:italic;">//true</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br></div></div><h3 id="获取属性名" tabindex="-1">获取属性名 <a class="header-anchor" href="#获取属性名" aria-label="Permalink to &quot;获取属性名&quot;">​</a></h3><p>使用 <code>Object.getOwnPropertyNames</code> 可以获取对象的属性名集合</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> hd</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> { </span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&#39;love&#39;</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;">year</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">2010</span><span style="color:#ABB2BF;"> }</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> names</span><span style="color:#56B6C2;"> =</span><span style="color:#E5C07B;"> Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">getOwnPropertyNames</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">hd</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">names</span><span style="color:#ABB2BF;">)</span><span style="color:#7F848E;font-style:italic;">// [&quot;name&quot;, &quot;year&quot;]</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><h3 id="assign" tabindex="-1">assign <a class="header-anchor" href="#assign" aria-label="Permalink to &quot;assign&quot;">​</a></h3><p>使用 <code>Object.assign</code> 静态方法从一个或多个对象复制属性</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> hd</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> { </span><span style="color:#E06C75;">a</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">1</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;">b</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">2</span><span style="color:#ABB2BF;"> };</span></span>
<span class="line"><span style="color:#E06C75;">hd</span><span style="color:#56B6C2;"> =</span><span style="color:#E5C07B;"> Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">assign</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">hd</span><span style="color:#ABB2BF;">, { </span><span style="color:#E06C75;">f</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">1</span><span style="color:#ABB2BF;"> }, { </span><span style="color:#E06C75;">m</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">9</span><span style="color:#ABB2BF;"> });</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">hd</span><span style="color:#ABB2BF;">); </span><span style="color:#7F848E;font-style:italic;">//{a: 1, b: 2, f: 1, m: 9}</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><h3 id="计算属性" tabindex="-1">计算属性 <a class="header-anchor" href="#计算属性" aria-label="Permalink to &quot;计算属性&quot;">​</a></h3><p>对象属性可以通过表达式计算定义，这在动态设置属性或执行属性方法时很好用。</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> id</span><span style="color:#56B6C2;"> =</span><span style="color:#D19A66;"> 0</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#ABB2BF;">  [</span><span style="color:#98C379;">`id-</span><span style="color:#C678DD;">${</span><span style="color:#E06C75;">id</span><span style="color:#56B6C2;">++</span><span style="color:#C678DD;">}</span><span style="color:#98C379;">`</span><span style="color:#ABB2BF;">]: </span><span style="color:#E06C75;">id</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#ABB2BF;">  [</span><span style="color:#98C379;">`id-</span><span style="color:#C678DD;">${</span><span style="color:#E06C75;">id</span><span style="color:#56B6C2;">++</span><span style="color:#C678DD;">}</span><span style="color:#98C379;">`</span><span style="color:#ABB2BF;">]: </span><span style="color:#E06C75;">id</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#ABB2BF;">  [</span><span style="color:#98C379;">`id-</span><span style="color:#C678DD;">${</span><span style="color:#E06C75;">id</span><span style="color:#56B6C2;">++</span><span style="color:#C678DD;">}</span><span style="color:#98C379;">`</span><span style="color:#ABB2BF;">]: </span><span style="color:#E06C75;">id</span></span>
<span class="line"><span style="color:#ABB2BF;">};</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">);</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><h3 id="for-in" tabindex="-1">for/in <a class="header-anchor" href="#for-in" aria-label="Permalink to &quot;for/in&quot;">​</a></h3><p>使用<code>for/in</code>遍历对象属性</p><h3 id="for-of" tabindex="-1">for/of <a class="header-anchor" href="#for-of" aria-label="Permalink to &quot;for/of&quot;">​</a></h3><p><code>for/of</code>用于遍历迭代对象，不能直接操作对象。但<code>Object</code>对象的<code>keys/</code>values/entries方法返回的是迭代对象。</p><h3 id="工厂函数" tabindex="-1">工厂函数 <a class="header-anchor" href="#工厂函数" aria-label="Permalink to &quot;工厂函数&quot;">​</a></h3><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">function</span><span style="color:#61AFEF;"> stu</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">name</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#C678DD;">  return</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">    name</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#61AFEF;">    show</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#E5C07B;">      console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#ABB2BF;">    }</span></span>
<span class="line"><span style="color:#ABB2BF;">  };</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> lisi</span><span style="color:#56B6C2;"> =</span><span style="color:#61AFEF;"> stu</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;李四&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">lisi</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">show</span><span style="color:#ABB2BF;">();</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> zhangsan</span><span style="color:#56B6C2;"> =</span><span style="color:#61AFEF;"> stu</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;zhangsan&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">xj</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">show</span><span style="color:#ABB2BF;">();</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><h3 id="构造函数" tabindex="-1">构造函数 <a class="header-anchor" href="#构造函数" aria-label="Permalink to &quot;构造函数&quot;">​</a></h3><p>和工厂函数相似构造函数也用于创建对象，它的上下文为新的对象实例。</p><ul><li>构造函数名每个单词首字母大写即<code>Pascal</code> 命名规范</li><li><code>this</code>指当前创建的对象</li><li>不需要返回<code>this</code>系统会自动完成</li><li>需要使用<code>new</code>关键词生成对象</li></ul><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">function</span><span style="color:#61AFEF;"> Student</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">name</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#E5C07B;">  this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">name</span><span style="color:#56B6C2;"> =</span><span style="color:#E06C75;"> name</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#E5C07B;">  this</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">show</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> function</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#E5C07B;">    console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#ABB2BF;">  };</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;">  //不需要返回，系统会自动返回</span></span>
<span class="line"><span style="color:#7F848E;font-style:italic;">  // return this;</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> lisi</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Student</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;李四&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">lisi</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">show</span><span style="color:#ABB2BF;">();</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> zhangsan</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Student</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;zhangsan&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">xj</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">show</span><span style="color:#ABB2BF;">();</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><h3 id="对象函数" tabindex="-1">对象函数 <a class="header-anchor" href="#对象函数" aria-label="Permalink to &quot;对象函数&quot;">​</a></h3><p>在<code>JS</code>中函数也是一个对象</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">function</span><span style="color:#61AFEF;"> hd</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">name</span><span style="color:#ABB2BF;">) {}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">hd</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">toString</span><span style="color:#ABB2BF;">());</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">hd</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">length</span><span style="color:#ABB2BF;">);</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br></div></div><p>函数是由系统内置的 <code>Function</code> 构造函数创建的</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">function</span><span style="color:#61AFEF;"> hd</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">name</span><span style="color:#ABB2BF;">) {}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">hd</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">constructor</span><span style="color:#ABB2BF;">);</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><p>下面是使用内置构造函数创建的函数</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> User</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Function</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">`name`</span><span style="color:#ABB2BF;">,</span><span style="color:#98C379;">`</span></span>
<span class="line"><span style="color:#98C379;">  this.name = name;</span></span>
<span class="line"><span style="color:#98C379;">  this.show = function() {</span></span>
<span class="line"><span style="color:#98C379;">    return this.name;</span></span>
<span class="line"><span style="color:#98C379;">  };</span></span>
<span class="line"><span style="color:#98C379;">`</span></span>
<span class="line"><span style="color:#ABB2BF;">);</span></span>
<span class="line"></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> lisi</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> User</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;李四&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">lisi</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">show</span><span style="color:#ABB2BF;">());</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><h2 id="属性特征" tabindex="-1">属性特征 <a class="header-anchor" href="#属性特征" aria-label="Permalink to &quot;属性特征&quot;">​</a></h2><h3 id="查看特征" tabindex="-1">查看特征 <a class="header-anchor" href="#查看特征" aria-label="Permalink to &quot;查看特征&quot;">​</a></h3><p>使用 <code>Object.getOwnPropertyDescriptor</code>查看对象属性的描述。</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">  name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;love&quot;</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">  age</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">18</span></span>
<span class="line"><span style="color:#ABB2BF;">};</span></span>
<span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> desc</span><span style="color:#56B6C2;"> =</span><span style="color:#E5C07B;"> Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">getOwnPropertyDescriptor</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">, </span><span style="color:#98C379;">&quot;name&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">JSON</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">stringify</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">desc</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">null</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">2</span><span style="color:#ABB2BF;">));</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>使用 <code>Object.getOwnPropertyDescriptors</code>查看对象所有属性的描述</p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">    name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;love&quot;</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">    age</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">18</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> desc</span><span style="color:#56B6C2;"> =</span><span style="color:#E5C07B;"> Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">getOwnPropertyDescriptors</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">JSON</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">stringify</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">desc</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">null</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">2</span><span style="color:#ABB2BF;">));</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br></div></div><p>属性包括以下四种特性</p><table tabindex="0"><thead><tr><th>特性</th><th>说明</th><th>默认值</th></tr></thead><tbody><tr><td>configurable</td><td>能否使用 delete、能否修改属性特性、或能否修改访问器属性</td><td>true</td></tr><tr><td>enumerable</td><td>对象属性是否可通过 for-in 循环，或 Object.keys() 读取</td><td>true</td></tr><tr><td>writable</td><td>对象属性是否可修改</td><td>true</td></tr><tr><td>value</td><td>对象属性的默认值</td><td>undefined</td></tr></tbody></table><h3 id="设置特征" tabindex="-1">设置特征 <a class="header-anchor" href="#设置特征" aria-label="Permalink to &quot;设置特征&quot;">​</a></h3><p>使用<code>Object.defineProperty</code> 方法修改属性特性，通过下面的设置属性 name 将不能被遍历、删除、修改。</p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">    name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;love&quot;</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"><span style="color:#E5C07B;">Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">defineProperty</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">, </span><span style="color:#98C379;">&quot;name&quot;</span><span style="color:#ABB2BF;">, {</span></span>
<span class="line"><span style="color:#E06C75;">    value</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;you&quot;</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">    writable</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">false</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">    enumerable</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">false</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">    configurable</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">false</span></span>
<span class="line"><span style="color:#ABB2BF;">});</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><p>使用 <code>Object.defineProperties</code> 可以一次设置多个属性，具体参数和上面介绍的一样。</p><h3 id="禁止添加" tabindex="-1">禁止添加 <a class="header-anchor" href="#禁止添加" aria-label="Permalink to &quot;禁止添加&quot;">​</a></h3><p><code>Object.preventExtensions</code> 禁止向对象添加属性</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span><span style="color:#ABB2BF;">;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">  name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;love&quot;</span></span>
<span class="line"><span style="color:#ABB2BF;">};</span></span>
<span class="line"><span style="color:#E5C07B;">Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">preventExtensions</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">user</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">age</span><span style="color:#56B6C2;"> =</span><span style="color:#D19A66;"> 18</span><span style="color:#ABB2BF;">; </span><span style="color:#7F848E;font-style:italic;">//Error</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br></div></div><p><code>Object.isExtensible</code> 判断是否能向对象中添加属性</p><h3 id="封闭对象" tabindex="-1">封闭对象 <a class="header-anchor" href="#封闭对象" aria-label="Permalink to &quot;封闭对象&quot;">​</a></h3><p>Object.seal()<code>方法封闭一个对象，阻止添加新属性并将所有现有属性标记为 </code>configurable: false</p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">    name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&quot;love&quot;</span><span style="color:#ABB2BF;">,</span></span>
<span class="line"><span style="color:#E06C75;">    age</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">18</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"></span>
<span class="line"><span style="color:#E5C07B;">Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">seal</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">JSON</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">stringify</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">getOwnPropertyDescriptors</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">), </span><span style="color:#D19A66;">null</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">2</span><span style="color:#ABB2BF;">))</span></span>
<span class="line"></span>
<span class="line"><span style="color:#E5C07B;">Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">seal</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">Object</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">isSealed</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">user</span><span style="color:#ABB2BF;">))</span></span>
<span class="line"><span style="color:#C678DD;">delete</span><span style="color:#E5C07B;"> user</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">name</span><span style="color:#7F848E;font-style:italic;"> //Error</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><p><code>Object.isSealed</code> 如果对象是密封的则返回 <code>true</code>，属性都具有 <code>configurable: false</code>。</p><h3 id="冻结对象" tabindex="-1">冻结对象 <a class="header-anchor" href="#冻结对象" aria-label="Permalink to &quot;冻结对象&quot;">​</a></h3><p><code>Object.freeze</code> 冻结对象后不允许添加、删除、修改属性，writable、configurable 都标记为<code>false</code></p><p><code>Object.isFrozen()</code>方法判断一个对象是否被冻结</p><h2 id="属性访问器" tabindex="-1">属性访问器 <a class="header-anchor" href="#属性访问器" aria-label="Permalink to &quot;属性访问器&quot;">​</a></h2><p>getter 方法用于获得属性值，setter 方法用于设置属性，这是 JS 提供的存取器特性即使用函数来管理属性。</p><ul><li>用于避免错误的赋值</li><li>需要动态监测值的改变</li><li>属性只能在访问器和普通属性任选其一，不能共同存在</li></ul><h3 id="getter-setter" tabindex="-1">getter/setter <a class="header-anchor" href="#getter-setter" aria-label="Permalink to &quot;getter/setter&quot;">​</a></h3><p>用户的年龄数据使用访问器监控控制</p><div class="language-js line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">js</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#98C379;">&quot;use strict&quot;</span></span>
<span class="line"><span style="color:#C678DD;">const</span><span style="color:#E5C07B;"> user</span><span style="color:#56B6C2;"> =</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E06C75;">    data</span><span style="color:#ABB2BF;">: { </span><span style="color:#E06C75;">name</span><span style="color:#ABB2BF;">: </span><span style="color:#98C379;">&#39;后盾人&#39;</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;">age</span><span style="color:#ABB2BF;">: </span><span style="color:#D19A66;">null</span><span style="color:#ABB2BF;"> },</span></span>
<span class="line"><span style="color:#C678DD;">    set</span><span style="color:#61AFEF;"> age</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">value</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#C678DD;">        if</span><span style="color:#ABB2BF;"> (</span><span style="color:#C678DD;">typeof</span><span style="color:#E06C75;"> value</span><span style="color:#56B6C2;"> !=</span><span style="color:#98C379;"> &quot;number&quot;</span><span style="color:#56B6C2;"> ||</span><span style="color:#E06C75;"> value</span><span style="color:#56B6C2;"> &gt;</span><span style="color:#D19A66;"> 100</span><span style="color:#56B6C2;"> ||</span><span style="color:#E06C75;"> value</span><span style="color:#56B6C2;"> &lt;</span><span style="color:#D19A66;"> 10</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#C678DD;">            throw</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Error</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;年龄格式错误&quot;</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#ABB2BF;">        }</span></span>
<span class="line"><span style="color:#E5C07B;">        this</span><span style="color:#ABB2BF;">.</span><span style="color:#E5C07B;">data</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">age</span><span style="color:#56B6C2;"> =</span><span style="color:#E06C75;"> value</span></span>
<span class="line"><span style="color:#ABB2BF;">    },</span></span>
<span class="line"><span style="color:#C678DD;">    get</span><span style="color:#61AFEF;"> age</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#C678DD;">        return</span><span style="color:#98C379;"> `年龄是: </span><span style="color:#C678DD;">${</span><span style="color:#E5C07B;"> this</span><span style="color:#ABB2BF;">.</span><span style="color:#E5C07B;">data</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">age</span><span style="color:#C678DD;"> }</span><span style="color:#98C379;">`</span></span>
<span class="line"><span style="color:#ABB2BF;">    }</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"><span style="color:#E5C07B;">user</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">age</span><span style="color:#56B6C2;"> =</span><span style="color:#D19A66;"> 99</span></span>
<span class="line"><span style="color:#E5C07B;">console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">log</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">user</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">age</span><span style="color:#ABB2BF;">);</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br></div></div><h2 id="代理拦截" tabindex="-1">代理拦截 <a class="header-anchor" href="#代理拦截" aria-label="Permalink to &quot;代理拦截&quot;">​</a></h2><p>代理（拦截器）是对象的访问控制，<code>setter/getter</code> 是对单个对象属性的控制，而代理是对整个对象的控制。</p><ul><li>读写属性时代码更简洁</li><li>对象的多个属性控制统一交给代理完成</li><li>严格模式下 <code>set</code> 必须返回布尔值</li></ul><h3 id="代理函数" tabindex="-1">代理函数 <a class="header-anchor" href="#代理函数" aria-label="Permalink to &quot;代理函数&quot;">​</a></h3><p>如果代理以函数方式执行时，会执行代理中定义 <code>apply</code> 方法。</p><ul><li>参数说明:函数，上下文对象，参数</li></ul><p>下面使用 <code>apply</code> 计算函数执行时间</p><div class="language-javascript line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">javascript</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#C678DD;">function</span><span style="color:#61AFEF;"> factorial</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">num</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#C678DD;">  return</span><span style="color:#E06C75;"> num</span><span style="color:#56B6C2;"> ==</span><span style="color:#D19A66;"> 1</span><span style="color:#C678DD;"> ?</span><span style="color:#D19A66;"> 1</span><span style="color:#C678DD;"> :</span><span style="color:#E06C75;"> num</span><span style="color:#56B6C2;"> *</span><span style="color:#61AFEF;"> factorial</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">num</span><span style="color:#56B6C2;"> -</span><span style="color:#D19A66;"> 1</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#ABB2BF;">}</span></span>
<span class="line"><span style="color:#C678DD;">let</span><span style="color:#E06C75;"> proxy</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Proxy</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">factorial</span><span style="color:#ABB2BF;">, {</span></span>
<span class="line"><span style="color:#61AFEF;">  apply</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">func</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;font-style:italic;">obj</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;font-style:italic;">args</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#E5C07B;">    console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">time</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;run&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">    func</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">apply</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;">obj</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;">args</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#E5C07B;">    console</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">timeEnd</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;run&quot;</span><span style="color:#ABB2BF;">);</span></span>
<span class="line"><span style="color:#ABB2BF;">  }</span></span>
<span class="line"><span style="color:#ABB2BF;">});</span></span>
<span class="line"><span style="color:#E5C07B;">proxy</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">apply</span><span style="color:#ABB2BF;">(</span><span style="color:#E5C07B;">this</span><span style="color:#ABB2BF;">, [</span><span style="color:#D19A66;">1</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">2</span><span style="color:#ABB2BF;">, </span><span style="color:#D19A66;">3</span><span style="color:#ABB2BF;">]);</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br></div></div><h3 id="vue原理" tabindex="-1">Vue原理 <a class="header-anchor" href="#vue原理" aria-label="Permalink to &quot;Vue原理&quot;">​</a></h3><div class="language-html line-numbers-mode"><button title="Copy Code" class="copy"></button><span class="lang">html</span><pre class="shiki one-dark-pro vp-code" style="background-color:#282c34;color:#abb2bf;" tabindex="0"><code><span class="line"><span style="color:#ABB2BF;">&lt;</span><span style="color:#E06C75;">body</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">    &lt;</span><span style="color:#E06C75;">form</span><span style="color:#D19A66;"> action</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">&quot;&quot;</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">        &lt;</span><span style="color:#E06C75;">input</span><span style="color:#D19A66;"> type</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">&quot;text&quot;</span><span style="color:#D19A66;"> v-model</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">&quot;title&quot;</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">        &lt;</span><span style="color:#E06C75;">input</span><span style="color:#D19A66;"> type</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">&quot;text&quot;</span><span style="color:#D19A66;"> v-model</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">&quot;title&quot;</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">    &lt;/</span><span style="color:#E06C75;">form</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">    &lt;</span><span style="color:#E06C75;">div</span><span style="color:#D19A66;"> v-bind</span><span style="color:#ABB2BF;">=</span><span style="color:#98C379;">&quot;title&quot;</span><span style="color:#ABB2BF;">&gt;&lt;/</span><span style="color:#E06C75;">div</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">&lt;/</span><span style="color:#E06C75;">body</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#ABB2BF;">&lt;</span><span style="color:#E06C75;">script</span><span style="color:#ABB2BF;">&gt;</span></span>
<span class="line"><span style="color:#C678DD;">    function</span><span style="color:#61AFEF;"> View</span><span style="color:#ABB2BF;">() {</span></span>
<span class="line"><span style="color:#C678DD;">        let</span><span style="color:#E06C75;"> proxy</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> new</span><span style="color:#61AFEF;"> Proxy</span><span style="color:#ABB2BF;">({}, {</span></span>
<span class="line"><span style="color:#61AFEF;">            get</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">obj</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;font-style:italic;">property</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"></span>
<span class="line"><span style="color:#ABB2BF;">            },</span></span>
<span class="line"><span style="color:#61AFEF;">            set</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">obj</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;font-style:italic;">property</span><span style="color:#ABB2BF;">, </span><span style="color:#E06C75;font-style:italic;">value</span><span style="color:#ABB2BF;">) {</span></span>
<span class="line"><span style="color:#E5C07B;">                document</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">querySelectorAll</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">`[v-model=&quot;</span><span style="color:#C678DD;">${</span><span style="color:#E06C75;"> property</span><span style="color:#C678DD;"> }</span><span style="color:#98C379;">&quot;]`</span><span style="color:#ABB2BF;">).</span><span style="color:#61AFEF;">forEach</span><span style="color:#ABB2BF;">((</span><span style="color:#E06C75;font-style:italic;">item</span><span style="color:#ABB2BF;">) </span><span style="color:#C678DD;">=&gt;</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E5C07B;">                    item</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">value</span><span style="color:#56B6C2;"> =</span><span style="color:#E06C75;"> value</span></span>
<span class="line"><span style="color:#ABB2BF;">                })</span></span>
<span class="line"><span style="color:#E5C07B;">                document</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">querySelectorAll</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">`[v-bind=&quot;</span><span style="color:#C678DD;">${</span><span style="color:#E06C75;"> property</span><span style="color:#C678DD;"> }</span><span style="color:#98C379;">&quot;]`</span><span style="color:#ABB2BF;">).</span><span style="color:#61AFEF;">forEach</span><span style="color:#ABB2BF;">((</span><span style="color:#E06C75;font-style:italic;">item</span><span style="color:#ABB2BF;">) </span><span style="color:#C678DD;">=&gt;</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E5C07B;">                    item</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">innerHTML</span><span style="color:#56B6C2;"> =</span><span style="color:#E06C75;"> value</span></span>
<span class="line"><span style="color:#ABB2BF;">                })</span></span>
<span class="line"><span style="color:#ABB2BF;">            }</span></span>
<span class="line"><span style="color:#ABB2BF;">        })</span></span>
<span class="line"><span style="color:#E5C07B;">        this</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">init</span><span style="color:#56B6C2;"> =</span><span style="color:#C678DD;"> function</span><span style="color:#ABB2BF;"> () {</span></span>
<span class="line"><span style="color:#C678DD;">            const</span><span style="color:#E5C07B;"> els</span><span style="color:#56B6C2;"> =</span><span style="color:#E5C07B;"> document</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">querySelectorAll</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&quot;[v-model]&quot;</span><span style="color:#ABB2BF;">)</span></span>
<span class="line"><span style="color:#E5C07B;">            els</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">forEach</span><span style="color:#ABB2BF;">(</span><span style="color:#E06C75;font-style:italic;">item</span><span style="color:#C678DD;"> =&gt;</span><span style="color:#ABB2BF;"> {</span></span>
<span class="line"><span style="color:#E5C07B;">                item</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">addEventListener</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&#39;keyup&#39;</span><span style="color:#ABB2BF;">, </span><span style="color:#C678DD;">function</span><span style="color:#ABB2BF;"> () {</span></span>
<span class="line"><span style="color:#E06C75;">                    proxy</span><span style="color:#ABB2BF;">[</span><span style="color:#E5C07B;">this</span><span style="color:#ABB2BF;">.</span><span style="color:#61AFEF;">getAttribute</span><span style="color:#ABB2BF;">(</span><span style="color:#98C379;">&#39;v-model&#39;</span><span style="color:#ABB2BF;">)] </span><span style="color:#56B6C2;">=</span><span style="color:#E5C07B;"> this</span><span style="color:#ABB2BF;">.</span><span style="color:#E06C75;">value</span></span>
<span class="line"><span style="color:#ABB2BF;">                })</span></span>
<span class="line"><span style="color:#ABB2BF;">            })</span></span>
<span class="line"><span style="color:#ABB2BF;">        }</span></span>
<span class="line"><span style="color:#ABB2BF;">    }</span></span>
<span class="line"><span style="color:#C678DD;">    new</span><span style="color:#61AFEF;"> View</span><span style="color:#ABB2BF;">().</span><span style="color:#61AFEF;">init</span><span style="color:#ABB2BF;">()</span></span>
<span class="line"><span style="color:#ABB2BF;">&lt;/</span><span style="color:#E06C75;">script</span><span style="color:#ABB2BF;">&gt;</span></span></code></pre><div class="line-numbers-wrapper" aria-hidden="true"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br></div></div></div></div></main><footer class="VPDocFooter" data-v-39a288b8 data-v-e257564d><!--[--><!--]--><div class="edit-info" data-v-e257564d><!----><div class="last-updated" data-v-e257564d><p class="VPLastUpdated" data-v-e257564d data-v-e98dd255>最后更新: <time datetime="2024-12-30T14:20:32.000Z" data-v-e98dd255></time></p></div></div><nav class="prev-next" aria-labelledby="doc-footer-aria-label" data-v-e257564d><span class="visually-hidden" id="doc-footer-aria-label" data-v-e257564d>Pager</span><div class="pager" data-v-e257564d><a class="VPLink link pager-link prev" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%9F%BA%E6%9C%AC%E7%B1%BB%E5%9E%8B.html" data-v-e257564d><!--[--><span class="desc" data-v-e257564d>上一篇</span><span class="title" data-v-e257564d>基本类型</span><!--]--></a></div><div class="pager" data-v-e257564d><a class="VPLink link pager-link next" href="/frontend/js%E5%9F%BA%E7%A1%80/%E5%B8%B8%E7%94%A8%E6%8A%80%E5%B7%A7.html" data-v-e257564d><!--[--><span class="desc" data-v-e257564d>下一篇</span><span class="title" data-v-e257564d>常用技巧</span><!--]--></a></div></nav></footer><!--[--><!--]--></div></div></div><!--[--><!--]--></div></div><!----><!--[--><!--]--></div></div>
    
    
  </body>
</html>